Field of the Invention
Embodiments of the present invention relate to a flow directing device for a cooking appliance with a fan mechanism, which comprises at least one fan wheel in an interior of the cooking appliance for circulating atmosphere, comprising at least one first flow directing member for subdividing the interior into a pressure chamber with the fan wheel and a cooking chamber, wherein the first flow directing member leaves free at least one suction port for sucking atmosphere from the cooking chamber into the pressure chamber in the area of the fan wheel and at least one blow-off port for blowing atmosphere from the pressure chamber into the cooking chamber when the fan wheel is in operation, at least one second flow directing member, which is mounted onto the fan mechanism or molded with the fan mechanism in the area of the suction port of the first flow directing member in order to improve the flow from the cooking chamber into the pressure chamber by forcing an axial main flow in the suction zone of the fan mechanism, and a cooking appliance with such a flow directing device.
Description of the Related Art
In the prior art, numerous measures for optimising a flow in the interior of a cooking appliance are known. Usually, a first flow directing member is used in the form of an air directing plate between a cooking chamber and a fan chamber or pressure chamber, which comprises a central suction port and leaves open blow-off ports facing the walls of the interior, so that a fan wheel arranged in the pressure chamber can suck atmosphere from the cooking chamber through the suction port and blow it out via the blow-off ports.
DE 203 14 818 U1, for example, deals with the targeted blowing of atmosphere from the pressure chamber into the cooking chamber via specially arranged blow-off ports in the first flow directing member. DE 10 2007 023 767, which is not pre-published, also deals with the blow-off ports of a first flow directing member, wherein movable elements should be arranged in blow-off ports, which move depending on the pressure progression in the cooking chamber. Another approach can be found, for example, in DE 203 09 268 U1 by using second flow directing members in the fan chamber in which a breaking up of the eddies should be forced while passing through a blow-off port between the pressure chamber and the cooking chamber, so that eddies spread out in the cooking chamber. Second flow directing members for forcing a homogeneous flow in the cooking chamber are also described in DE 203 12 031 U1.
A further flow directing device can be found, for example, in DE 10 2004 004 393 B4, in which a first flow directing member is in the form of a single piece with a second flow directing member. More precisely, the edge of the first flow directing member is turned in the form of an air directing plate in the area of its suction port to form a flow directing nozzle. This nozzle is a suction nozzle and is designed to improve the suction of atmosphere from a cooking chamber into a fan chamber of a cooking appliance. However, the disadvantage here is that a gap must be present at all times between a rotating fan wheel in the pressure chamber on the one hand, and the suction nozzle on the air directing plate on the other, in order to avoid damage. With cooking appliances in industrial kitchens in particular, this gap is large enough, due to tolerances, to enable atmosphere to flow from the pressure chamber directly into the suction area of the fan wheel, i.e., it is not directed via a blow-off port into the cooking chamber and via the suction port of the air directing plate into the suction area of the fan wheel, so that a short-circuit occurs with the atmosphere, which flows in from the cooking chamber through the suction port of the air directing plate. For this reason, this flow, which penetrates through the gap, is also known as a short-circuit flow, and occurs at a very sensitive point in the suction area of the fan wheel, i.e., in the deflection area of a main flow from the cooking chamber into the pressure chamber, more precisely, where a deflection occurs from a radial direction into an axial direction of the main flow. Thus, the short-circuit flow runs transverse to the main flow in the suction area of the fan wheel, so that it narrows the main flow and can itself cause a displacement and swirling of the main flow, which leads to an overall reduction in the effectiveness of the circulation of cooking chamber atmosphere by the fan wheel.
Generic flow directing devices for cooking appliances are described in EP 1 767 869 A2 and DT 25 19 604, wherein in both cases, a first flow directing member spreads out at least up to the suction port of a fan wheel, and in the case of DT 25 19 604, even extends into the suction port, while the second flow directing member is provided in the form of an outer contour of the fan wheel.